Man has always looked for some way to explain life and what happened in the world about him. In primitive times, this was done by creating myths in which nature was controlled by spirits.

The first people who tried to think about the forces of nature not as the acts of spirits but simply as forces were the ancient Greeks. But they tried to discover truth by observation and reasoning alone, without making experiments. So they made many errors and accepted many theories that explained most of the facts, but not all.